Some time back I wanted to build a replica WWII 1911a1 and tried using the Rock Island but had to give up quickly because of the enlarged ejection port. I believe they all still have that feature.

If you want to start as close as you can get for the money the Springfield Armory model is the best bet. Even at that, I have replaced the mainspring housing to add the lanyard loop, hammer, safety and slide release to get the proper checkering and grips of course to get rid of the horrible SA engraved grips. Still, a collector can spot it at some distance as a modern made pistol. The park finish is just not quite right. Time and lanolin will make the finish better.